The country also has 402 kilometers (249 miles) of coastline on the Bight of Biafra, part of the Atlantic Ocean. The topography of Cameroon is varied, ranging from tropical rain forests in the south to mountainous highlands in some western central regions, and semi-arid savanna in the far north.
The Ionisphere bounces radio waves back to earth and regulates the amount of radiation that gets to the lower atmospheres. It all depends on the Sun's activity. The stratosphere is what actually protects us from the UV rays of the sun.
The lower most region of the ionosphere extending from about 50 km to 90 km is the D-region, which principally absorbs radio waves. Above the D layer is the E-region extending from 90 km to 150 km.